A walkout is when a group of people decide to leave a place or stop doing something they are supposed to do because they are not happy with what is happening or they want something to change. For example, if you and your friends are playing a game and you don't like how your friend is playing, you might decide to stop playing and leave until your friend changes how they are playing. People might also do a walkout if they want to show other people that they are serious about the thing they want to change. It's like saying, "We're not going to be a part of this until we get what we think is right."